The Molecular Clinical Trials Shared Resource (MCTSR) is a highly-specialized resource that provides expert advice and technological and experimental support for the conduct of molecular assays of drug targets and drug activity within prospective clinical trials. The MCTSR, collects, processes and analyzes samples from patients treated within prospective clinical trials of molecular targeted therapies. Resource support extends throughout the entire research process from initial study design and planning through to the implementation and interpretation of results. The MCTSR is currently supporting 17 clinical trials within the SJCCC and cooperative groups and is engaging all four SJCCC programs that treat patients. During the current reporting period the resource provided molecular biology services to papers reporting seven Phase I clinical trials and five Phase II studies, of which seven were published in the Journal of Clinical Oncology. The resource contributed major molecular biology services to a further nine papers, including studies published in Nature, Nature Medicine, and Cancer Cell.